SAM Type Interface #920

Jay-Lokhande · 2025-06-18T18:26:10Z

This PR's objective is to create a SAM type interface in log4cats

core/shared/src/main/scala/org/typelevel/log4cats/JsonLike.scala

morgen-peschke · 2025-06-19T23:38:21Z

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

+final case class KernelLogLevel(name: String, value: Double) {
+  def namePadded: String = KernelLogLevel.padded(this)
+
+  KernelLogLevel.add(this)
+}


issue (structure): I'm sick right now, but we should get on a call towards the end of next week and go over bincompat.

Case classes are wonderful for applications, but we're going to tend to avoid them because they don't play nicely with bincompat.

agreed 💯

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

morgen-peschke · 2025-06-19T23:40:11Z

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

+  def add(level: KernelLogLevel): Unit = synchronized {
+    val length = level.name.length
+    map += level.name.toLowerCase -> level
+    if (length > maxLength) {
+      maxLength = length
+      padded = map.map { case (_, level) =>
+        level -> level.name.padTo(maxLength, ' ').mkString
+      }
+    } else {
+      padded += level -> level.name.padTo(maxLength, ' ').mkString
+    }
+  }


issue: I'm not convinced we need to support dynamically adding log levels, or looking them up by name.

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

morgen-peschke · 2025-06-20T00:36:10Z

core/shared/src/main/scala/org/typelevel/log4cats/LoggerKernel.scala

+  final def logTrace(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Trace, record)
+  final def logDebug(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Debug, record)
+  final def logInfo(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Info, record)
+  final def logWarn(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Warn, record)
+  final def logError(record: Log.Builder => Log.Builder): F[Unit] =
+    log(KernelLogLevel.Error, record)


suggestion (naming): If we do end up needing these, we should simplify down the names

Suggested change

final def logTrace(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Trace, record)

final def logDebug(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Debug, record)

final def logInfo(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Info, record)

final def logWarn(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Warn, record)

final def logError(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Error, record)

final def trace(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Trace, record)

final def debug(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Debug, record)

final def info(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Info, record)

final def warn(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Warn, record)

final def error(record: Log.Builder => Log.Builder): F[Unit] =

log(KernelLogLevel.Error, record)

lets keep it until final change, I tried to change as suggested but its giving error due to duplicates

js-console/src/main/scala/org/typelevel/log4cats/console/ConsoleLogger.scala

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

Jay-Lokhande · 2025-06-20T13:15:50Z

Thank you for all the suggestions, I will rework on it

… Logger

morgen-peschke · 2025-07-09T06:44:16Z

core/shared/src/main/scala/org/typelevel/log4cats/KernelLogLevel.scala

+  // For Java/legacy interop, if needed (not implicit)
+  val LevelOrdering: Ordering[KernelLogLevel] =
+    Ordering.by[KernelLogLevel, Int](_.value).reverse


Java interop is a non-issue, since attempting to use cats-effect from Java would be painful (at best) and the idioms are all sorts of incompatible.

There's an implicit which provides an Ordering[A] if there is an Order[A] in scope, so this can be removed.

morgen-peschke · 2025-08-26T02:08:54Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

    private var _timestamp: Option[FiniteDuration] = None
    private var _level: Option[KernelLogLevel] = None
-    private var _levelValue: Option[Int] = None
-    private var _message: Option[String] = None
+    private var _message: () => String = noopMessage


Question: is the use case of a log without a message something we want to support?

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

morgen-peschke · 2025-08-26T16:07:13Z

core/shared/src/main/scala/org/typelevel/log4cats/SamLogger.scala

+  ): SamLogger[F, Ctx] =
+    new SamLogger[F, Ctx] {
+      def log(level: KernelLogLevel, record: Builder => Builder): F[Unit] = {
+        val modifiedRecord = (builder: Builder) => {


Needing to materialize the log and manually copy over the full message hints to me that we may need to refine Builder.

Pretty sure this would materialize message as well, so that's something to check.

With the added adaptMessage method, this becomes:

def log(level: KernelLogLevel, record: Builder => Builder): F[Unit] = { l.log(level, record(_).adaptMessage(f)) }

morgen-peschke · 2025-08-26T16:34:43Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

+trait Log[Ctx] {
+  def timestamp: Option[FiniteDuration]
+  def level: KernelLogLevel
+  def message: String


This should probably be lazy all the way to the edge.

Suggested change

def message: String

def message: () => String

morgen-peschke · 2025-08-26T16:35:13Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

+  def unsafeThrowable: Throwable
+  def unsafeContext: Map[String, Ctx]


I didn't see these used anywhere, I think we can probably remove them.

morgen-peschke · 2025-08-26T16:36:16Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

+        contextMap: Map[String, A]
+    )(implicit E: Context.Encoder[A, Ctx]): Builder[Ctx] =
+      contextMap.foldLeft(this) { case (builder, (k, v)) => builder.withContext(k)(v) }
+


Implementing withModifiedString and addContext will be easier if we add some helpers here.

Suggested change

def adaptTimestamp(f: FiniteDuration => FiniteDuration): Builder[Ctx]

def adaptLevel(f: KernelLogLevel => KernelLogLevel): Builder[Ctx]

def adaptMessage(f: String => String): Builder[Ctx]

def adaptThrowable(f: Throwable => Throwable): Builder[Ctx]

def adaptContext(f: Map[String, Ctx] => Map[String, Ctx]): Builder[Ctx]

def adaptFileName(f: String => String): Builder[Ctx]

def adaptClassName(f: String => String): Builder[Ctx]

def adaptMethodName(f: String => String): Builder[Ctx]

def adaptLine(f: Int => Int): Builder[Ctx]

morgen-peschke · 2025-08-26T16:36:55Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

+  private class MutableBuilder[Ctx] extends Builder[Ctx] {
+    private var _timestamp: Option[FiniteDuration] = None
+    private var _level: Option[KernelLogLevel] = None
+    private var _message: Option[String] = None


To keep this lazy, we'd need to update here as well

Suggested change

private var _message: Option[String] = None

private var _message: () => String = () => ""

morgen-peschke · 2025-08-26T16:37:36Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

+    private var _level: Option[KernelLogLevel] = None
+    private var _message: Option[String] = None
+    private var _throwable: Option[Throwable] = None
+    private val _context: mutable.Map[String, Ctx] = mutable.Map.empty[String, Ctx]


Using a builder here will make things a bit easier when writing adaptContext

Suggested change

private val _context: mutable.Map[String, Ctx] = mutable.Map.empty[String, Ctx]

private var _context: mutable.Builder[(String, Ctx), Map[String, Ctx]] = Map.newBuilder[String, Ctx]

morgen-peschke · 2025-08-26T16:38:28Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

+
+  private class MutableBuilder[Ctx] extends Builder[Ctx] {
+    private var _timestamp: Option[FiniteDuration] = None
+    private var _level: Option[KernelLogLevel] = None


This can be simplified, since we have a default value we're going to use anyway.

Suggested change

private var _level: Option[KernelLogLevel] = None

private var _level: KernelLogLevel = KernelLogLevel.Info

morgen-peschke · 2025-08-26T16:39:25Z

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala

+      _line = if (line > 0) Some(line) else None
+      this
+    }
+  }


Here's the adapt* methods

Suggested change

}

override def adaptTimestamp(f: FiniteDuration => FiniteDuration): Builder[Ctx] = {

_timestamp = _timestamp.map(f)

this

}

override def adaptLevel(f: KernelLogLevel => KernelLogLevel): Builder[Ctx] = {

_level = f(_level)

this

}

override def adaptMessage(f: String => String): Builder[Ctx] = {

_message = () => f(_message())

this

}

override def adaptThrowable(f: Throwable => Throwable): Builder[Ctx] = {

_throwable = _throwable.map(f)

this

}

override def adaptContext(f: Map[String, Ctx] => Map[String, Ctx]): Builder[Ctx] = {

_context = _context.mapResult[Map[String, Ctx]](f)

this

}

override def adaptFileName(f: String => String): Builder[Ctx] = {

_fileName = _fileName.map(f)

this

}

override def adaptClassName(f: String => String): Builder[Ctx] = {

_className = _className.map(f)

this

}

override def adaptMethodName(f: String => String): Builder[Ctx] = {

_methodName = _methodName.map(f)

this

}

override def adaptLine(f: Int => Int): Builder[Ctx] = {

_line = _line.map(f)

this

}

}

morgen-peschke · 2025-08-26T16:45:40Z

core/shared/src/main/scala/org/typelevel/log4cats/SamStructuredLogger.scala

+    val builder = (b: Log.Builder[String]) => {
+      var current = b.withMessage(msg)
+      ctx.foreach { case (k, v) => current = current.withContext[String](k)(v) }
+      current
+    }
+    kernel.logTrace(builder)


Might be worth exercising the methods on Log.Builder to see if they pull their weight.
For example, this can be simplified to:

Suggested change

val builder = (b: Log.Builder[String]) => {

var current = b.withMessage(msg)

ctx.foreach { case (k, v) => current = current.withContext[String](k)(v) }

current

}

kernel.logTrace(builder)

kernel.logTrace(_.withMessage(msg).withContextMap(ctx))

Jay-Lokhande added 12 commits June 18, 2025 15:50

Added Logger Kernel Initial File

485b98b

sbt scalafmt

8d8223f

added withMethodName method

f6e9d55

added more SAM type specific files

e7f0be4

changed LogLevel to remove conflict

7f6dc0e

going back to LogLevel name

9c3c243

original WriterTLogger

9908c00

deleted DefferedLogLevel

4fb2850

build.sbt

fc58670

scalafmt

23b2094

sbt scalafmtSbt

3f1f34c

added KernelLogLevel

7961c15

morgen-peschke reviewed Jun 20, 2025

View reviewed changes

iRevive mentioned this pull request Jun 20, 2025

Logs module typelevel/otel4s#994

Open

15 tasks

add new samlogger interface based on old and poc logger

a5708c3

Jay-Lokhande added 7 commits June 23, 2025 07:15

add SamStructuredLogger that delegates to LoggerKernel, with original…

649468d

… Logger

modify log with parameterized with the context type

ac5aaee

change datatype double to int and use cats Order

53dda4f

update LoggerKernel to use new Log.scala

634de7d

update LogRecord and Recordable to use paramerterized Log

b7f0d10

update ConsoleLogger to original, JsonLike

859753b

remove unused Context.Encoder

ac1a39b

lenguyenthanh mentioned this pull request Jun 30, 2025

Allow adding effect's contextual environment to the log context #800

Open

morgen-peschke reviewed Jul 9, 2025

View reviewed changes

Jay-Lokhande and others added 5 commits August 7, 2025 18:09

Merge branch 'typelevel:main' into feature/log4cats-sam-type

3beb5f7

remove JsonLike Structure instead bypass it direct

44ab02b

modify files to adapt new change

10b0c81

update log.scala

4b746e2

update recordable

2ad479c

update Log.scala

842bb7e

morgen-peschke reviewed Aug 26, 2025

View reviewed changes

core/shared/src/main/scala/org/typelevel/log4cats/Log.scala Outdated Show resolved Hide resolved

Jay-Lokhande added 2 commits August 26, 2025 12:53

update log.scala

fd6bab1

update Log.scala

63ba4c4

morgen-peschke reviewed Aug 26, 2025

View reviewed changes

Jay-Lokhande added 7 commits September 4, 2025 16:46

update with the suggested changes

5b85513

use builder for the context

022f96b

add sourcecode stable version

3d00cf9

sbt scalafmt

17cb902

sbt scalafmt

3df4963

add foreach loop instead forALL

4602d56

resolve sourcecode scalanavative error

f139d0c

		def unsafeThrowable: Throwable
		def unsafeContext: Map[String, Ctx]

+    def adaptTimestamp(f: FiniteDuration => FiniteDuration): Builder[Ctx]
+    def adaptLevel(f: KernelLogLevel => KernelLogLevel): Builder[Ctx]
+    def adaptMessage(f: String => String): Builder[Ctx]
+    def adaptThrowable(f: Throwable => Throwable): Builder[Ctx]
+    def adaptContext(f: Map[String, Ctx] => Map[String, Ctx]): Builder[Ctx]
+    def adaptFileName(f: String => String): Builder[Ctx]
+    def adaptClassName(f: String => String): Builder[Ctx]
+    def adaptMethodName(f: String => String): Builder[Ctx]
+    def adaptLine(f: Int => Int): Builder[Ctx]

	private var _message: Option[String] = None
	private var _message: () => String = () => ""

	private val _context: mutable.Map[String, Ctx] = mutable.Map.empty[String, Ctx]
	private var _context: mutable.Builder[(String, Ctx), Map[String, Ctx]] = Map.newBuilder[String, Ctx]

	private var _level: Option[KernelLogLevel] = None
	private var _level: KernelLogLevel = KernelLogLevel.Info

-  }
+    override def adaptTimestamp(f: FiniteDuration => FiniteDuration): Builder[Ctx] = {
+      _timestamp = _timestamp.map(f)
+      this
+    }
+    override def adaptLevel(f: KernelLogLevel => KernelLogLevel): Builder[Ctx] = {
+      _level = f(_level)
+      this
+    }
+    override def adaptMessage(f: String => String): Builder[Ctx] = {
+      _message = () => f(_message())
+      this
+    }
+    override def adaptThrowable(f: Throwable => Throwable): Builder[Ctx] = {
+      _throwable = _throwable.map(f)
+      this
+    }
+    override def adaptContext(f: Map[String, Ctx] => Map[String, Ctx]): Builder[Ctx] = {
+      _context = _context.mapResult[Map[String, Ctx]](f)
+      this
+    }
+    override def adaptFileName(f: String => String): Builder[Ctx] = {
+      _fileName = _fileName.map(f)
+      this
+    }
+    override def adaptClassName(f: String => String): Builder[Ctx] = {
+      _className = _className.map(f)
+      this
+    }
+    override def adaptMethodName(f: String => String): Builder[Ctx] = {
+      _methodName = _methodName.map(f)
+      this
+    }
+    override def adaptLine(f: Int => Int): Builder[Ctx] = {
+      _line = _line.map(f)
+      this
+    }
+  }

SAM Type Interface #920

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SAM Type Interface #920

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Jay-Lokhande commented Jun 18, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Jay-Lokhande commented Jun 20, 2025

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Jay-Lokhande commented Jun 18, 2025 •

edited

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